I am encountering an issue with my Spring Boot web service when sending multiple requests at once. Some requests fail, but when debugging, they go through successfully.

Stack:

• Spring Boot version: 2.7.4
• Embedded server: Tomcat 9.0.65
• IDE: IntelliJ IDEA
• Client: Postman

When sending a request, I receive the following errors in my logs:

2025-03-31 16:22:29.271 DEBUG 16768 --- [nio-8082-exec-1] o.apache.coyote.http11.Http11Processor   : Error parsing HTTP request header
2025-03-31 16:22:29.272 DEBUG 16768 --- [nio-8082-exec-1] o.apache.coyote.http11.Http11Processor   : Error state [CLOSE_CONNECTION_NOW] reported while processing request

Stack trace:

java.io.EOFException: null
    at .apache.tomcat.util.NioEndpoint$NioSocketWrapper.fillReadBuffer(NioEndpoint.java:1340) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at .apache.tomcat.util.NioEndpoint$NioSocketWrapper.read(NioEndpoint.java:1227) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at .apache.coyote.http11.Http11InputBuffer.fill(Http11InputBuffer.java:805) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at .apache.coyote.http11.Http11InputBuffer.parseRequestLine(Http11InputBuffer.java:360) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at .apache.coyote.http11.Http11Processor.service(Http11Processor.java:271) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    ...

When I send multiple requests at the same time, some of them fail, but they pass when debugging.

Code:

Controller endpoint:

@PostMapping("api/synchro/process")
public ResponseEntity<String> processEntries(@RequestBody List<Synchro> entries) {
    try {
        for (Synchro entry : entries) {
            System.out.println(entry.getId());
            synchroService.processSynchroEntry(entry);
        }
        return ResponseEntity.ok("PROCESSED");
    } catch (Exception e) {
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
                .body("Error processing entries: " + e.getMessage());
    }
}

Service method:

@Transactional
public void processSynchroEntry(Synchro entry) {
    String eventType = entry.getEventType().toUpperCase();
    String data = entry.getData();
    String tableName = entry.getTableName();
    switch (eventType) {
        case "INSERT" -> this.handleInsert(tableName, data);
        case "UPDATE" -> this.handleUpdate(tableName, data);
        case "DELETE" -> this.handleDelete(tableName, data);
        default -> throw new IllegalArgumentException("Unsupported event type: " + eventType);
    }
}

Dynamic Insert Query Execution:

protected void handleInsert(String tableName, String data) {
    try {
        JsonNode dataNode = this.objectMapper.readTree(data);
        StringBuilder query = new StringBuilder("INSERT INTO ");
        query.append(tableName).append(" (");
        MapSqlParameterSource params = new MapSqlParameterSource();
        StringBuilder columns = new StringBuilder();
        StringBuilder values = new StringBuilder();
        Iterator<Map.Entry<String, JsonNode>> it = dataNode.fields();

        while(it.hasNext()) {
            Map.Entry<String, JsonNode> field = it.next();
            if (columns.length() > 0) {
                columns.append(", ");
                values.append(", ");
            }
            columns.append(field.getKey());
            values.append(":" + field.getKey());
            params.addValue(field.getKey(), field.getValue().asText());
        }

        query.append(columns).append(") VALUES (").append(values).append(")");
        this.namedParameterJdbcTemplate.update(query.toString(), params);
    } catch (Exception e) {
        throw new RuntimeException("Error processing insert", e);
    }
}

What I've tried:

• Checked the request format: Requests are sent correctly via Postman.
• Enabled Spring Boot debug logs: Logs confirm that some requests fail with EOFException.
• Tested different concurrency levels: When sending requests one by one, they succeed. When sending them in bulk, some fail.
• Validated JSON payloads: All JSON data sent is properly formatted.
• Tried increasing Tomcat connection settings:

server.tomcat.max-threads=200
server.tomcat.accept-count=100
server.connection-timeout=60000

Questions:

• What could be causing these EOFExceptions when sending multiple requests?
• Could this be related to transaction handling or how Tomcat manages connections?
• Are there any known Spring Boot/Tomcat issues that might cause this behavior?
• Any insights or suggestions would be greatly appreciated!

 public class Synchro {
    @Id
    @GeneratedValue(
        strategy = GenerationType.IDENTITY
    )
    @Column(
        name = "id",
        unique = true,
        nullable = false
    )
    private @NotNull(
    message = "Id ne peut pas être null"
) Integer id;
    @Column(
        name = "eventType",
        length = 100,
        nullable = false
    )
    private @NotNull(
    message = "EventType ne peut pas être null"
) String eventType;
    @Column(
        name = "data",
        nullable = false
    )
    private @NotNull(
    message = "Data ne peut pas être null"
) String data;
    @Temporal(TemporalType.TIMESTAMP)
    @Column(
        name = "createdAt"
    )
    private @NotNull(
    message = "CreatedAt ne peut pas être null"
) Date createdAt;
    @Temporal(TemporalType.TIMESTAMP)
    @Column(
        name = "updatedAt"
    )
    private Date updatedAt;
    @Column(
        name = "status",
        length = 20,
        nullable = false
    )
    private @NotNull(
    message = "Status ne peut pas être null"
) String status;
    @Column(
        name = "tableName",
        length = 100,
        nullable = false
    )
    private @NotNull(
    message = "TableName ne peut pas être null"
) String tableName;
    @Transient
    private String source;